Is my homebrew "Charger" fighter archetype balanced?

Question

I was looking at the mounted fighter subclass and realized that none of them have anything to do with mounted combat. So I decided to make my own subclass and was wondering if I could get some good objective feedback to better determine whether it's over/under powered, needs tweaking, or is in a good place compared to other fighter archetypes.

Is my homebrew "Charger" fighter archetype balanced?

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Charger

The charger is made for mounted combat. Unlike the other mounted archetypes which are made for “mounted combat”, the charger is made for use on a mount in combat.

Bonus Proficiency

At 3rd level, choose one of the following skills to become proficient in: Animal Handling, Perception, Survival, Persuasion, or Insight.

Bind

At 3rd level, you bind to the spirit of a mount to gain the following benefits:

• When you receive healing, your mount is healed by the same amount.
• You can summon your mount once per long rest (even if it died), with all its stuff.

Maintenance Expert

At 3rd level, the cost of all mount-related expenses (stabling, feed, saddles, mounts, etc...) is halved.

Negate Reaction

At 7th level, you don’t trigger reactions after moving 20 feet in a straight line, and enemies have disadvantage on reactions against you if you move 10 feet in a straight line. If you start your movement fleeing from a enemy within 5 feet of you, your mount can make an attack. The target must succeed on a DC 5 Strength saving throw or be knocked prone, or if your mount has a charge ability the DC is increased by 5.

Continuous Charge

At 7th level, you can attack while moving once every 10 feet, and you can charge through an enemy letting your mount attack. The target must succeed on a DC 5 Strength saving throw or be knocked prone letting your mount attack again, or if your mount has a charge ability the DC is increased by 10. This does not count towards the aforementioned 10 feet.

Bound Feet

At 10th level, you choose between 5 different feats: Mounted Combat, Charger, Healer, Alert, or Mobile. Mobile applies to your mount and to ranged weapons.

Focus Attack

At 15th level, you can make two attacks as one combining the damage and the attack bonus.

Legendary Action

At 18th level, you get one legendary action.

Answer 1

Short answer: No.

Nearly every ability you provide is overpowered.

Bind - This Find Steed that doesn't require a spells lot to create and can be done at will. While not every spell applies to it, healing does.

Maintenance Expert - This is a pretty underpowered 3rd level ability and will likely only become an issue at tables that require mundane maintenance.

Negate Reaction - This is basically giving you a 'free' disengage and free reaction attack. That's quite a lot and is overpowered.

Continuous Charge - THis is granting you additional attacks that you normally wouldn't have and greatly boosts your action economy beyond the baseline.

Focus Attack - This is also incredibly powerful. Allowing you to stack your bonuses into a single attack basically turns this into a near-guaranteed hit (1s aside) with massive damage.

Legendary Action - No PC build gets anything like this. Not even Level 20 capstones approach this.

Homebrew thoughts

It may make some sense to look at the Ranger Beastmaser or revised Beast conclave to give you some ideas on a PC class that has a strong connection to an animal. It'll give you some guidance as to how to structure a homebrew and to make equivalences in your development. But in general, I'd recommend staying away from things that aren't generally available to players at all - like legendary actions.